Although a hardware system may itself be deterministic such that its behaviour may be determined completely by inputs to the system, the same may not be true of the environment in which the hardware system exists. Typically, the behaviour of the environment is dependent upon such a large number of inputs that it is not possible to provide a deterministic model of the behaviour of the environment which therefore appears to be a non-deterministic system. It is also possible that the environment is mathematically non-deterministic, in the sense that even if all of the inputs could be assessed, the outputs are still not known.
The present invention finds particular application in synthesising the behaviour of hardware systems within their environment for example for the development-testing of a hardware system. It is also possible to apply the invention to modelling the behaviour of software systems for testing purposes.